1. Field of the Invention
The present invention is generally related to a marine propulsion device and, more particularly, to a hydraulic actuation system that routes a hydraulic conduit through the body of a portion of the marine propulsion device structure.
2. Description of the Related Art
Those skilled in the art of marine propulsion devices are familiar with many different hydraulic applications related to marine vessels and propulsion devices and, in addition, are familiar with various optional techniques that can be used to conduct the flow of pressurized hydraulic fluid between components of the marine propulsion device.
U.S. Pat. No. 3,599,595, which issued to James on Aug. 17, 1971, describes an outdrive for boats which has a hydraulic pump including an eccentric ring which is rotatable to change the path of fluid flow under pressure so that the direction of drive of the motor can be easily reversed. Hydraulic fluid may be subjected to pressure with structure prior to communication thereof to the hydraulic pump. A transom bracket and sterndrive housing support are connected so as to provide pivotal movement of the sterndrive housing along two mutually perpendicular axes so that the sterndrive housing will remain in the water even when the boat negotiates a sharp turn, the transom bracket being provided with couplings to accommodate fluid flow therethrough and a fluid restraining recess to allow recirculation of cooling water through a driving engine carried by the boat.
U.S. Pat. No. 4,363,629, which issued to Hall et al. on Dec. 14, 1982, describes a hydraulic system for an outboard motor with sequentially operating tilt and trim means. The device comprises a transom bracket adapted to be connected to a boat transom, a first pivot connecting a stern bracket to the transom bracket for pivotal movement of the stern bracket relative to the transom bracket about a first pivot axis which is horizontal when the transom bracket is boat mounted, a second pivot connecting a swivel bracket to the stern bracket below the first pivot for pivotal movement of the swivel bracket with the stern bracket and relative to the stern bracket about a second pivot axis parallel to the first pivot axis and a king pin pivotally connecting a propulsion unit including a rotatably mounted propeller to the swivel bracket for steering movement of the propulsion unit relative to the swivel bracket about a generally vertical axis and for common pivotal movement with the swivel bracket in a vertical plane about the first and second horizontal axes.
U.S. Pat. No. 4,645,464, which issued to Rawlings on Feb. 24, 1987, describes a steering and tilting means for a marine propulsion device. The device comprises a gimbal housing adapted to be fixedly mounted on a boat transom, a gimbal ring pivotally mounted on the gimbal housing for pivotal movement relative to the gimbal housing about a generally vertical steering axis and a support arm extending rearwardly from the lower end of the gimbal ring.
U.S. Pat. No. 5,203,730, which issued to Kuragaki on Apr. 20, 1993, describes a tilting system for an outboard drive unit. A conduit arrangement in a hydraulic tilting system for an outboard drive unit is described wherein a plurality of connecting members are provided, one mounted at the lower end of the gimbal housing and two mounted on the outer periphery of the gimbal housing higher than the upper connecting member but lower than the tilt shaft on the gimbal ring.
U.S. Pat. No. 6,176,170, which issued to Uppgard et al. on Jan. 23, 2001, discloses a hydraulic actuator with shock absorbing capability. The actuator comprises a cylinder with first and second pistons slidably disposed therein. The first and second pistons are movable relative to each other. A poppet is supported by the first piston and is movable relative to the first piston. In response to hydraulic fluid pressure within a passage of the first piston, the poppet can be caused to move in a direction which opens a passage through the first piston to allow the first piston to move relative to the second piston in response to a shock impact such as that which can result from an outboard motor striking a submerged or floating object.
U.S. Pat. No. 6,296,535, which issued to Bland et al. on Oct. 2, 2001, describes a tilt-trim subsystem for boats using a sterndrive system. The subsystem assembly is affixed to an outdrive of a sterndrive that may be supported by a gimbal unit and may be configured to rotate about a predetermined axis to impart a desired trim or tilt to the drive system. The tilt-trim assembly has one respective end thereof configured to pivotally receive one anchor pin supported by the outdrive. The assembly includes one or more cylinders having one end thereof pivotally connected to another anchor pin so that when the cylinder is actuated the outdrive and the tilt-trim subsystem assembly are jointly rotated about the predetermined axis.
U.S. Pat. No. 6,454,620, which issued to Theisen et al. on Sep. 24, 2002, discloses an integrated external hydraulic trimming and steering system for an extended sterndrive transom assembly. The marine propulsion system is provided with a drive unit that is attachable to a transom of a marine vessel and provided with steering cylinder assemblies and trimming cylinder assemblies which are connected to a common location on a structure member, such as a gimbal ring. This arrangement improves the geometric relationship between the steering and trimming functions. In addition, the hydraulic steering system is provided with pressure relief valves that are located at the transom of the marine vessel in order to shorten the distance of the hydraulic conduits extending between the pressure relief valves and the steering cylinders.
U.S. Pat. No. 6,468,120, which issued to Hasl et al. on Oct. 22, 2002, describes a single cylinder trim/tilt assembly. It includes a shield assembly for being secured to a transom of the boat. A gimbal ring is pivotally coupled to the shield assembly at an axis of rotation. A drive frame is pivotably connected to the gimbal ring so that the drive frame pivots in conjunction with the gimbal ring. A single trim cylinder is included that has a first end connected to the gimbal ring and a second end connected to the drive frame. The trim cylinder has a cylinder rod and a cylinder housing and the cylinder rod is movable within the cylinder housing.
U.S. Pat. No. 6,607,410, which issued to Neisen et al. on Aug. 19, 2003, describes a single cylinder tilt-trim assembly for boats using a sterndrive system. A sterndrive system is described which has an outdrive rotatable about a generally horizontal axis to impart a desired trim or tilt to the drive system. The system includes a gimbal ring that defines an inner region. The gimbal ring is configured to pivotally receive a first anchor pin. A tilt-trim assembly is affixed to the outdrive and the tilt-trim assembly has one respective end thereof configured to pivotally receive a second anchor pin supported by the outdrive.
U.S. Pat. No. 6,656,004, which issued to Bland et al. on Dec. 2, 2003, describes a tilt-trim subsystem for boats using a sterndrive system. The assembly is fixed to an outdrive of a sterndrive which may be supported by a gimbal unit and may be configured to rotate about a predetermined axis to impart a desired trim or tilt to the drive system. The assembly has one end thereof configured to pivotally receive one anchor pin supported by the outdrive. The assembly includes one or more cylinders having one end thereof pivotally connected to another anchor pin so that when the cylinder is actuated the outdrive and the tilt-trim subsystem assembly are jointly rotated about the predetermined axis.
U.S. Pat. No. 6,830,492, which issued to Magee et al. on Dec. 14, 2004, discloses a marine drive trim cylinder with a two stage damping system. The system is provided for a trim cylinder mount of a marine drive unit. The mounting bushings comprise inner and outer tubes with an elastomeric material disposed between the inner and outer tubes. The elastomeric material is structure to provide a soft rate of stiffness in response to relatively light loads, such as shifting loads, and a harder rate of stiffness in response to higher loads, such as during high thrust loads or wide open throttle operation of a marine vessel.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.